So-called Boris bikes provide a health benefit to cyclists that outweighs the hazards of riding them, a study has found. The positive effects of the London cycle-hire scheme are greatest for older users, the research shows.

Scientists balanced improvements to health from the physical activity of cycling
with the potentially harmful effects of physical injury and inhaling
traffic fumes. The results showed that the benefits far outweighed the
negatives, at least when assessing injury rates for people riding Boris
bikes. A slightly different picture emerged when injury rates for all
cycling in London were taken into account. Then, the net gains from
hiring bikes reduced – and disappeared altogether for women.

The London cycle hire scheme, sponsored by Barclays bank, was introduced in 2010 and championed by the city's mayor, Boris Johnson. His enthusiasm was such that the bicycles soon came to be known as "Boris bikes".

Dr Anna Goodman, from the London School of Hygiene and Tropical Medicine,
said: "When the cycle hire scheme was introduced, there were widespread
concerns that increasing the number of inexperienced cyclists in
central London would lead to higher injury rates.

"Our findings
are reassuring, as we found no evidence of this. On the contrary, our
findings suggest that the scheme has benefited the health of Londoners
and that cycle hire users are certainly not at higher risk than other
cyclists."

Currently around 10,000 Boris bikes are available
across 723 docking stations covering a large amount of greater London.
During the year the research was carried out, between April 2011 and
March 2012, more than half a million users made 7.4 million trips on the
rented bikes.

The study authors determined health benefits using a
disability adjusted life years, the number of years lost to life
through illness, disability and premature death.

The research, published in the British Medical Journal,
showed that riding Boris bikes led to a significant increase in healthy
living in men and a smaller gain for women. Co-author Dr James
Woodcock, from the Medical Research Council epidemiology unit at
Cambridge University, pointed out that the health benefit of Boris bikes
was lower in younger adults, who make up the majority of riders.

"One
reason for this is that many of the diseases affected by physical
activity, such as heart disease, are less common in younger people," he
said. "Even though older adults might be more at risk of injury than
younger adults, the benefits from being active increase much more
quickly.

"Reducing road traffic danger is another key factor. If
cycling in central London was as safe as in cities in the Netherlands,
the health benefits from initiatives like the cycle hire scheme would be
far more substantial.

"The Netherlands manages to achieve high
levels of cycling with low risks, not by focusing on helmets and hi-vis,
but by providing high quality infrastructure that physically protects
cyclists from busy, fast moving traffic."

Lack of exercise
has been linked to a wide range of health problems including heart
disease, stroke, diabetes, dementia, depression and cancer. Cycling is
said to provide a good way of incorporating physical activity into
everyday life.

Dr Janet Valentine, head of public health
and ageing at the MRC, said: "The health benefits of regular exercise
are undisputed. It is important that we conduct rigorous scientific
studies to assess the wider impacts of interventions designed to promote
health.

"Studies like this, which look at large amounts of data
from real-world scenarios, will help to develop future strategies to
bring about positive changes to our health."